Apparatus for needle punching sheet materials



March 14, 1961 J. L.. HOLLOWELL APPARATUS FOR NEEDLE PUNCHING SHEETMATERIALS Filed Jan. 8, 1959 2 Sheets-Sheet 1 FIG.2

INVENTOR JOSEPH L. HOLLOWELL ATTORNEY March 14, 1961 J. 1... HOLLOWELL2,974,393

APPARATUS FOR NEEDLE PUNCHING SHEET MATERIALS Filed Jan. 8, 1959 2Sheets-Sheet 2 FIG.4 FIG.5 F|G.6

INVENTOR JOSEPH L. HOLLOWELL ATTORNEY APPARATUS FOR NEEDLE PUNCHINGSHEET MATERIALS Joseph L. Hollowell, Cornwall on the Hudson, N.Y., as-

signor to E. I. du Pont de Nemours and Company, Wilmington, Del., acorporation of Delaware Filed Jan. 8, 1959, Ser. No. 785,657

3 Claims. (Cl. 28-4) This invention relates to needle punching and moreparticularly to an improved process and apparatus for needle punchingsheet materials, especially unwoven batts of fibers.

Felt-like sheet materials have been prepared for many years in thetextile industry by needle punching batts of carded or similarlyoriented natural fibers of materials such as, for example, hair, juteand sisal. These punched felt-like materials have been used, forexample, as carpet linings, insulating felts, slicker felts, cartridgewadding and the like. Recently, felt-like sheet materials have beenprepared for unwoven batts of synthetic fibers.

Basically, needle punching comprises piercing an unwoven batt of fiberswith a plurality of needles to orient individual or small groups offibers subtantially perpendicular to the plane of the batt therebygiving added strength to the unwoven structure. In its crudest form,this process can comprise punching the batt with a handoperatedinstrument comprising a substrate to which are fixed a plurality ofneedles. Usually, however, this operation is performed on a needle loomwhich basically comprises a large number of closely spaced needlessupported in position to be moved, and usually reciprocated, into andout of the batt of fibers.

In order to take full advantage of the needle punching operation and toorient fibers throughout the thickness of the batt substantiallyperpendicular to the plane of the batt, the needles must pass throughthe batt. Conventionally, a batt of unwoven fibers in a needle loom issupported on a plate called a bedplate which has a plurality of holes inits surface. During needle punching, the needles in the needle loom passthrough the batt of unwoven fibers and through the holes in thebedplate, thenyare withdrawn from the batt as the batt moves forwardthrough the loom. This type of structure inherently has severaldisadvantages. First, the needles in the needle loom must be positionedto reciprocate into and out of the holes in the bedplate. Thus, if oneor more of the needles become bent or are deflected by heavy fibers inthe batt being punched, the needles strike the edge of the holes in thebedplate and are broken. Secondly, this structure inherently limits theneedle density, that is, the number of needles per unit area in thepunching surface, for, obviously, there is a limit after which there isno more bedplate through which to drill holes. Necessarily, thislimitation in needle density also limits the number of punches persquare inch per stroke which can be made in the batt. Consequently,batts of unwoven fibers must either be run through the needle loomseveral times or they must be run very slowly therethrough. Thirdly, itis very difficult to punch very thin batts of fibers, particularlysynthetic fibers such as polytetrafluoroethylene, in a needle loom.Conventional needle looms greatly distort and stretch batts of syntheticfibers which have a low coefficient of friction and slide easily overone another and thus yield products with an uneven surface and density.

Since the aformentioned problems in needle-punching 2,974,393 PatentedMar. 14, 1961 solved by this invention are most acute when unwoven battsof fibers are punched, the following discussion deals primarily withsuch sheet materials; however, the following discussion applies equallywell to the needle punching of sheet materials generally such as, forexample, knitted fabrics, woven fabrics, coated fabrics, polymeric filmsand the like.

I have discovered an improved method and apparatus for needle punchingsheet materials, particularly unwoven batts of fibers. This method andapparatus make it possible to use a very high needle density and,consequently, make it possible to punch sheet materials at a much higherrate than that obtained by conventional methods and apparatuses. Thismethod and apparatus also eliminate the need for precise alignment ofthe needles in a loom with the holes in a bedplate. Also, certainembodiments of this invention are particularly suited for punching thinbatts of fibers, including synthetic fibers.

The improved process of this invention comprises supporting a sheetmaterial on a plurality of closely spaced, resilient, rod-like elementsand moving a plurality of needles into and out of the sheet material.The improved apparatus of this invention comprises a needle loom forpunching sheet materials which loom comprises a plurality of closelyspaced needles, means to move the needles into and out of the sheetmaterials and a plurality of closely spaced, resilient rod-like elementspositioned to support the sheet materials as the needles passtherethrough.

The improved apparatus of this invention is described in detailhereinafter by reference to a preferred embodiment shown in theaccompanying drawings wherein:

Figure 1 is a partial section in side elevation of an improved needleloom of this invention;

Figure 2 is a plan view of the needle loom shown in Figure 1; v

Figure 3 is an enlarged cross-section of the punching area in the needleloom shown in Figure 1;

Figures 4, 5 and 6 are side elevations of representative cross-sectionsof supporting members bearing a plurality of closely-spaced, resilient,rod-like elements; and

' Figure 7 is a schematic drawing of a spirally wrapped flexible beltbearing a plurality of closely spaced, resilient rod-like elements.

Theprojected height of the rod-like elements which 1 support the unwovenbatts is at least about equal to the maximum distance which the tips ofthe needles move below the surface of the unwoven batts being punched.Usually, the rod-like elements are about from 1 to 10,

and preferably 1 to 2 times this length. The cross-sec tionalconfiguration of the rod-like elements can be, for example, elliptical,square, triangular, round, oval or the like. Round or ellipticalrod-like elements are usually used and are preferred. The averagediameter of the elements usually decreases with the size of the fibersin the batts being punched; it also decreases as the inherent resiliencyof the materials from which the elements are formed increases. Usuallyelements having an average diameter of 0.01 to 0.05 inch, and preferably0.01 to 0.02 inch are used. The density of the rod-like elements, thatis, elements per unit area, varies with the size of the fibers beingneedle punched and depends upon whether. or not the unwoven batts arefed on a carrier such as,

for example, a thin flexible film of polyvinyl chloride, polyethyleneterephthalate, or similar polymeric materials, a woven fabric or thelike. When a carrier is used,

in which case the needles pass through the batt, the car-' rier and thenbetween the rod-like elements, densities on the order of 10 elements persquare inch can be used. With short fibers of small denier, densities onthe order' of 300 or more elements per square inch are desirable.

Preferably about from 100 to 300 elements per square inch are used.

As shown in Figures 4, and 6, the rod-like elements can have a varietyof shapes, that is, vertical configurations. The elements can be, forexample, kneed, straight or curved. When the rod-like elements haverounded points or a carrier is fed with the batt, particularly when highdensities of the elements are used, the angle between the elements andthe plane of the batts can approach 90. In needle looms such as thepreferred embodiments shown in the drawings in which the rod-likeelements are pulled through the loom along with the non-woven batt asdescribed hereinafter, the rod-like elements preferably project backwardtoward the feed side of the loom at an angle a of about from 20 to 80.(See Figures 4, 5 and 6.) This configuration reduces distortion in thebatts. Kneed rod-like elements such as those shown in Figure 4, themajor portion of which project backward and upward at an angle or ofabout 20 to 80 and a lower minor portion of which project forward andupward at an angle 6 of about 20 to 90 are particularly preferredbecause they have outstanding strength and resiliency. In the punchingarea, the batts and the substrate bearing the rod-like elements aresubstantially parallel. Thus, for simplicity, in Figures 4, 5 and 6, theangles a and 5 are shown with respect to such substrates.

The rod-like elements can be formed from any of a wide variety ofresilient materials such as, for example, steel and steel alloys,copper-beryllium alloys, tungsten or even rod-like resilient fibers ofpolymers such as polyamides, polyethylene terephthalate, celluloseacetate or polyformaldchyde. Elements of steel and steel alloys arepreferred.

The rod-like elements may be fixed to any of a wide variety ofsubstrates. For hand punching, or even in needle looms, the elements maybe fixed to a rigid substrate such as, for example, fabric and fabriclaminates impregnated with phenol-formaldehyde, melamine-formaldehydeand urea formaldehyde resins and substrates of, for example, steel,copper, brass, bronze, aluminum, tungsten and wood or the like. Therod-like elements can also be fixed to the bedplate or a needle loom.They can also be fixed to flexible substrates supported on one of theaforementioned rigid substrates. Preferably, as shown in the drawings,the rod-like elements are fixed to flexible belt which moves through theloom with the non-woven batts being punched. Examples of flexiblesubstrates are those of leather, fabrics coated with rubber, bothnatural and synthetic, or any of the wide variety of other conventionalcoating materials such as, for example, vinyl chloride homopolymers andcopolymers, polyurethanes, vinyl acetate homopolymers and copolymers,nitrocellulose, polytetrafluoroethylene, cellulose acetate butyrate,polyethylene or the like; unsupported sheets and films of theaforementioned or other polymeric materials or even wire screens orbelts to which the rodlike projections are aflixed.

Turning now to the drawings, the needle loom depicted in Figures 1, 2and 3 consists of needles 1, held in a needle board 2, which in turn isfastened to a top beam 3. The needle assembly consisting of needles 1,needle board 2, and top beam 3 is reciprocated substantially verticallybetween top beam guides 4 by connecting rods 5 which are connected todrive shaft 6 through eccentric straps 9 and eccentrics 10. As the driveshaft 6 is turned by a suitable prime mover (not shown) through pulley7, eccentrics 10 rotate within the eccentric straps 9 which movetheconnecting rods 5 and the needle assembly. As the needlesreciprocate, they pass downwardly through the holes in the stationarystripper plate 11. Figure 1 shows the position of the needles 1 as theybegin their downward stroke. Figure 3 shows the needles after they havepassed through the stripper plate 11, the unwoven batt of fibers 23 andbetween the rod-like elements 12;

As shown in Figure 1, feed crank 13 fastened to eccentric 10 isrotatably connected to clutch lever 14 which is also rotatably connectedto clutch pitman 15. When the drive shaft 6 and eccentric 10 turn,clutch lever 14 causes clutch pitman 15 to oscillate back and forth.Ratchet 16 attached to clutch pitman 15 engages gear 17 andintermittently rotates rear draw roll 18. Rear draw roll 18intermittently rotates forward feed roll 19 through chain drive 20.Thus, the needle assembly, the feed mechanism and rear draw roll 18 areall driven from eccentric 10. In the embodiment shown in Figures 1, 2and 3, the rod-like elements 12 are fixed to an endless belt 21 whichpasses around and is driven by friction contact with draw roll 18 andfeed roll 19. In the punching area underneath needles 1, the endlessbelt 21 is supported by bedplate 22.

In operation, the loose unwoven batt of fibers 23 fed from roller 24 isdeposited on the tips of rod-like elements 12 which bear the batt intoand through the punching area beneath needles 1. As the batt passesbeneath the needles 1 they reciprocate passing downwardly through thebatt 23 and among the rod-like elements 12, then upwardly back throughthe batt. The vertical movement of the batt 23 is limited by bedplate 22and stripper plate 11. Stripper plate 11 can be a drilled or slottedplate, a tensioned wire grid or the like; the bedplate 22 can be anysubstantially rigid supporting member. After being punched by thereciprocating needles 1, the batt 23 is carried to and wound on roll 25.If the batt is fed on a carrier, the carrier can be stripped from thebatt and wound on roll 26 as the batt is wound on roll 25.

Figure 7 shows a variation in the manner in which the rod-like elements12 can be positioned in the needle loom. In Figure 7, the rod-likeelements 12 (for clarity, shown only in part) are supported on anendless belt 21 which is spirally wrapped around draw roll 18 and feedroll 19. Individual spirals are held in position and in close proximitywith each other by thin ridges 27 on the rolls 18 and 19. Roller 28 isused to feed and position the endless belt 21 as it runs from draw roll18 back to the feed roll 19 on the other side of the punching area.Roller 28 or another roller can also be used to regulate the tension inthe endless belt 21. This embodiment shown in Figure 7 is particularlypreferred because it helps keep the tension in the endless belt 21 equalthroughout the width of the punching area.

The improved method and apparatus of this invention eliminate thenecessity of precisely positioning needles, make it possible to needlepunch sheet materials more quickly than with known methods andapparatuses and produce less distortion in the sheet being needlepunched. With the improved method and apparatus of this invention, it ispossible to use needle densities of 100 or even higher needles persquare inch as compared with conventional apparatuses which, forexample, usually have densities of less than about 5 to 10 needles persquare inch. Also, with the process and apparatus of this invention, itis possible to punch very thin batts, for example, ,5 inch or lessformed from fibers as fine as 0.1 denier or less. The apparatus andprocess of this invention can be used with any of a wide variety offibers, both natural and synthetic, and is particularly suited forsynthetic fibers such as, for example, those of polytetrafluoroethylene,rayon, polyacrylonitrile, polyethylene terephthalate, nylon and thelike.

The following example is intended to illustrate the utility of thisinvention and is not intended to limit it in any way.

Example A loose batt comprising 10% by weight of 1.5 denier and byweight of 0.5 denier polyethylene terephthalate staple fibers, 1 /2inches long is carded and crosslapped into a non-woven batt of about 48slivers weighing about 9.2 ounces per square yard. The loose batt isthen fed on a polymeric film about 1 mil thick to a needle loomsubstantially similar to that shown in Figures 1 and 2 equipped with anendless, flexible, spirally wrapped belt bearing rod-like elements asshown in Figure 7. The rod-like elements are steel and of the kneed typesuch as those shown in Figure 4 having a diameter of about 0.014 inch.The elements project upward and forward at an angle 5 of about 70 aboutinch, then upward and backward at an angle on of about 60 about inch.The density of the elements is about 208 elements per square inch.

The unwoven batt is punched about 3,000 times per square inch with 40gauge single-barbed steel felting needles to yield a product about 35mils thick weighing about 4.1 ounces per square yard and having atensile strength of 5.3 pounds per linear inch in the machine directionand about 2.5 pounds per linear inch in the cross-machine direction. Theproduct is substantially uniform throughout and free from unevenstretching and distortion.

materials as said needles pass therethrough, the upper major portion ofsaid rod-like elements projecting upwardly and backwardly toward thefeed side of said loom at an angle of about 20 to with the plane of saidsheet materials and the lower minor portion of said rodlike elementsprojecting upwardly and forwardly at an angle of about 20 to with theplane of said sheet materials.

2. An apparatus of claim 1 wherein said rod-like elements have anaverage diameter of about 0.01 to 0.05 inch and a density of about fromto 300 elements per square inch.

3. In a needle loom for punching sheet materials, which loom comprises aplurality of closely spaced needles and means to move said needles intoand out of said sheet materials, the improvement which comprises anendless flexible carrier belt spirally wrapped around feed and drawrolls for said loom, said endless flexible carrier belt bearing aplurality of closely spaced rod-like elements positioned to support saidsheet materials as said needles pass therethrough.

References Cited in the file of this patent FOREIGN PATENTS 22,728 GreatBritain of 1891

